A card reader of a manual system is known in which a card provided with a magnetic stripe is manually inserted into a card insertion part and, at the time of insertion or extraction of the card, magnetic data in the magnetic stripe is read by a data read section. In this type of card reader, the reading operation is not repeated because the reading operation of the manually-operated card reader is assumed to be performed only once. Therefore, only one read decision reference value is set in this type of manual card reader.
The read decision reference value is a reference value for judging the level of the read signal, that is, for deciding whether the read signal is at a level that is to be demodulated. For example, the read decision reference value is determined by the read peak detection sensitivity or the read signal slice level. When the read peak detection sensibility is enhanced or when the read signal slice level is decreased, it is effective for reading a demagnetized or bent card. However, these methods are overly sensitive to external noises and the reading of the card is easily affected by an adverse influence. On the contrary, when the read peak detection sensibility is lowered or when the read signal slice level is increased, the reading of the card is minimally affected by the external noises. But these methods are not preferable for reading a demagnetized or bent card. Accordingly, in consideration of these matters, that is, in correlative consideration of the noise and the output level of the read signal, the read decision reference value is determined on the basis of experience.
However, since the conventional card reader is provided with only one read decision reference value, no matter how many times tried the card still will not be able to be read even though the normal operation is performed. Therefore, the reading rate of magnetic data is not satisfactory.